Conventionally, there has been provided an illumination apparatus which detects an illuminance and a presence or absence of a human by using an image sensor, and controls a light output from a light source based on the detection results (see, e.g., Japanese Patent Application Publication No. 2002-289377).
The illumination apparatus described in Japanese Patent Application Publication No. 2002-289377 includes a TV camera (image sensor) using a charge coupled device (CCD), a complementary metal oxide semiconductor (CMOS) or the like, and detects the illuminance and the presence or absence of a human on the basis of an image captured by the image sensor. This illumination apparatus controls the light output from the light source based on the detected illuminance if a human presence is detected, and turns off the light source if no human presence is detected. In this way, the illumination apparatus turns off the light source when no human is present to thereby suppress a power consumption.
However, if the light source is turned off, e.g., at night time at which a light (e.g., external light) other than a light from the light source is not incident, it becomes difficult to ensure the illuminance required for the image sensor to capture an image. In this way, when the image sensor cannot capture an image, the detection of the presence or absence of a human by using the image cannot be accomplished.